This invention relates to a cylinder lock and particularly relates to a cylinder lock having an adjustable tailpiece.
Typically, a cylindrical lock assembly includes a rollback or sleeve onto which is assembled a knob or lever which functions as a lock operator. A spring-biased plate extends partially from within the sleeve and through a slot in the sleeve and serves to retain the knob or lever with the sleeve. The knob or sleeve may be removed from the sleeve by selective depression of the plate into the sleeve through an access hole in the knob or sleeve. Since removal of the knob or lever will expose the inner portions of the assembly and thereby provide possible unauthorized entry, it is important that the knob or lever be removable only by an authorized person.
The cylindrical lock assembly has a cylinder lock which includes a tailpiece which is rotatable upon operation of the lock by use of a key. The tailpiece typically functions upon key operation of the lock to retract a latch bolt to permit opening of a door to which the assembly is mounted. In addition, the tailpiece is positioned within the sleeve adjacent the spring-biased plate and prevents inward movement of the plate when the cylinder lock is in the locked condition. When the key is used to unlock the cylinder lock, the tailpiece is thereby rotated to a position which permits the depression of the spring-biased plate by use of an implement positioned through the access hole of the knob or lever.
Thus, the requirement that a key must be used in the cylinder lock to facilitate removal of the knob or lever is a significant security feature of such a system.
Due to the fixed location of the spring-biased plate within the sleeve and the slot through which it extends, the tailpiece must be in a precise orientation and location to prevent manipulation of the plate regardless of whether the cylinder lock is assembled with a knob or a lever.
Typically, in a lever arrangement, the key slot and a rib portion of the cylinder lock are oriented horizontally in which case the tailpiece is also oriented horizontally and is in proper orientation to prevent movement of the spring-biased plate. When the key is operated, the tailpiece is rotated to permit depression of the spring-biased plate and removal of the lever from the sleeve if desired.
In a knob arrangement, the key slot and rib portion are oriented in a vertical direction. However, the tailpiece must be in the horizontal orientation to preclude movement of the spring-biased plate.
Therefore, when it is desired to change from a lever-operated system to a knob-operated system, a cylinder lock of dedicated design must be provided for each system. This requires dual manufacturing, packaging and stocking. Also, it is an added cost to the ultimate customer who is changing from a lever to a knob system.
Thus, there is a need for versatile cylinder lock which can be used in both the knob-operated and the lever-operated systems.